A couple of years ago, in a moment either of boredom or temporary madness, I
set out to calculate T-stops on all my medium and large format lenses, 20+ in
all. To do this, I set a 16x19 in. light box in a vertical position, put the
lens to be calibrated on a Crown Graphic on a tripod 12 in. away, then measured
off the ground glass with a Sekonic Digi Master L-718 meter, using the Pinpoint
Attachment L-718PP, which is intended for exactly such measurements.
Guess what! I quit after the sixth or seventh lens, having failed to discover
any discrepancy greater than 0.2 of a stop between the marked f-stop and the
measured T-stop. Hardly worth bothering to note.
I've got a couple of 5x7 in. pieces of ground glass I've kept around for years
just in case I ever break one. I suppose I could cut out a small piece to
cover the film plane of an OM body, set everything up, drag out all the Zuikos
and see if...
Nah, I don't think so. Once on that fool's errand was enough. Maybe there's a
bigger difference with the Zuikos, or some of them, but it's not going to keep
me up nights worrying about it.
Walt
--
"Anything more than 500 yards from
the car just isn't photogenic." --
Edward Weston
-------------- Original message ----------------------
From: "Julian Davies" <julian_davies@xxxxxxxxxxxxxx>
>
> The daisy chain can be up to 9 guns, so yes it can continue.
> A T20 or 32 on the PBG2 can always take power from the PBG, irrespective of
> how it is connected to the camera.
> If you go for tripod mounted lighting, you either need to guarantee where
> the subject will be (eg leave bird - food to attract it) or use diffusers
> and go for wide-area lighting.
>
> I'll leave the F number debate for others, but if it is really important to
> you for flash, you would need T stop equivalences for each of your lenses.
> I've never seen that published for Zuikos (but I admit to never having
> looked for it).
>
> Julian
>
> ----- Original Message -----
> From: "Fernando Gonzalez Gentile" <fgnzalez@xxxxxxxxxxxxx>
> To: <olympus@xxxxxxxxxx>
> Sent: Saturday, January 22, 2005 7:00 PM
> Subject: [OM] Re: Simple questions about T45
>
>
> > on 22/01/2005 16:03, Julian Davies wrote:
> >
> >> You wouldn't need the TTL connector if you put a T32 on the shoe. You
> >> plug
> >> the Cord into the socket on the T32 instead! This goes against your off -
> >> axis requirement, however.
> > Would the PBG2 T-32 mounted profit of the 4 'C' cells too?
> > That's good news, but could a daisy chain be continued? For instance,
> > pluging a cord into the bottom socket of the PBG2 ->T20 adapter and so on
> > ?
> >>
> >> I carry mini tripods in my flash bag specifically to put T20 connectors
> >> and
> >> T32s on. Works well if there is something to put them on, and is probably
> >> less problematic than trying to get so many pieces onto the camera.
> > Well, I do the same.
> > But it all depends of which suject do you intend to shoot, having chosen
> > ASA
> > 100 film. Perhaps a bird of you know will land just there...
> > You're right, I'm getting into the trouble of assembling a complicated
> > puzzle. But how do I catch that small bird? Not a hummingbird, whose
> > behavior is highly predictable...
> >>
> >> For the guide number calculation, if the separation of the flashes is
> >> significant at the subject distance, the calculation becomes impossible
> >> for
> >> my limited abilities, so it's TTL or meter for me!
> > Alright, I agree with you; that's why I said it wouldn't quite reach a GN
> > 45.
> >
> >> If you go TTL the
> >> question of accuracy / consistency of the aperture markings becomes
> >> irrelevant.
> > But I see this just the other way round !!
> > Accuracy / consistency of the aperture markings have a mathematical reason
> > of their own. They should be as they must. TTL-OTF may override
> > inaccuracy,
> > but it was not intended to do so (both flash or Auto TTL-OTF)
> > And we still didn't clear up the reason for this peculiar apparent lack of
> > consistency.
> >
> > When I subscribed, there was a fellow listee whom I don't recall too well,
> > but always signed:
> > "Inquiring minds want to know"
> >
> > Fernando.
> >
> >
> >
> > ==============================================
> > List usage info: http://www.zuikoholic.com
> > List nannies: olympusadmin@xxxxxxxxxx
> > ==============================================
> >
>
>
>
> ==============================================
> List usage info: http://www.zuikoholic.com
> List nannies: olympusadmin@xxxxxxxxxx
> ==============================================
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|